Frequency conversion circuit, radio frequency wave receiver, and radio frequency transceiver

• US 20050117664A1
• Filed: 10/29/2004
• Published: 06/02/2005
• Est. Priority Date: 10/31/2003
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Kamiya, Shinji, Adan, Alberto O.
• Granted Patent: US 7,567,610 B2
• Time in Patent Office: Days
• US Class Current: 375/316
• CPC Class Codes: H03D 2200/0084 Lowering the supply voltage and saving power
• CPC Class Codes: H03D 7/1441 using field-effect transistors H03D7/145 takes precedence
• CPC Class Codes: H03D 7/1458 Double balanced arrangements, i.e. where both input signals are differential
• CPC Class Codes: H03D 7/1466 Passive mixer arrangements
• CPC Class Codes: H03D 7/165 at least two frequency changers being located in different paths, e.g. in two paths with carriers in quadrature combined with amplitude demodulation H03D1/2245, combined with angle demodulation H03D3/007; N-path filters H03H19/002
• CPC Class Codes: H04B 1/408 the transmitter oscillator frequency being identical to the receiver local oscillator frequency

Abstract

A frequency conversion circuit of the present invention includes: (i) a first mixer for mixing the radio frequency signal having a frequency f_RF with a first oscillation signal having a frequency f_LO1 so that the radio frequency signal is downconverted into an intermediate frequency signal; and (ii) a second mixer for mixing the intermediate frequency signal sent from the first mixer with two local oscillation signals so that the intermediate frequency signal is downconverted into two base-band signals having different phases. The second local oscillation signals have phases of 0° and 270°, respectively. These frequencies satisfies:
f_LO1=k×f_RF(k>1)
f_LO2=f_LO1/m, (m>1)
k=m/(m−1). This arrangement ensures (i) a small frequency conversion circuit that can be mounted on an integrated circuit, (ii) a radio frequency receiver including the frequency conversion circuit, and (iii) a radio frequency transceiver including the radio frequency receiver.

Claims

1. A frequency conversion circuit for downconverting a radio frequency signal having a desired frequency into two base-band signals having different phases, comprising:

a first mixer for mixing the radio frequency signal with a first oscillation signal so that the radio frequency signal is downconverted into an intermediate frequency signal; and

a second mixer for mixing the intermediate frequency signal received from the first mixer with two second local oscillation signals having different phases, respectively, so that the intermediate frequency signal is downconverted into the two base-band signals,

the two second local oscillation signals having phases of 0° and

270°

, respectively, and

f_LO1=k×

f_RF, f_LO2=f_LO1/m, and k=m/(m−

1) being satisfied, where f_RF indicates a frequency of the radio frequency signal, f_LO1 indicates a frequency of the first local oscillation signal, f_LO2 indicates frequencies of the second local oscillation signals, k indicates an arbitrary number satisfying k>

1, and m indicates an arbitrary number satisfying m>

1.

2. The frequency conversion circuit as set forth in claim 1, wherein:

m is an integer satisfying m=2ⁿ, where n is a positive integer.

3. The frequency conversion circuit as set forth in claim 1, further comprising:

an image signal removal filter for removing an image signal from an output signal of the first mixer.

4. The frequency conversion circuit as set forth in claim 1, further comprising:

an oscillator for generating the first local oscillation signal; and

a divider for dividing the frequency of the first local oscillation signal into 1/m so as to generate the second local oscillation signals having the phases of 0° and

270°

, respectively.

5. A radio frequency receiver for receiving a radio frequency carrier wave having a desired frequency, comprising:

a frequency conversion circuit for downconverting a radio frequency signal having a desired frequency into two base-band signals having different phases,

said frequency conversion circuit, including;

a first mixer for mixing the radio frequency signal with a first oscillation signal so that the radio frequency signal is downconverted into an intermediate frequency signal; and

a second mixer for mixing the intermediate frequency signal received from the first mixer with two second local oscillation signals having different phases, respectively, so that the intermediate frequency signal is downconverted into the two base-band signals,

the two second local oscillation signals having phases of 0° and

270°

, respectively, and

f_LO1=k×

f_RF, f_LO2=f_LO1/m, and k=m/(m−

1) being satisfied, where f_RF indicates a frequency of the radio frequency signal, f_LO1 indicates a frequency of the first local oscillation signal, f_LO2 indicates a frequency of the second local oscillation signal, k indicates an arbitrary number satisfying k>

1, and m indicates an arbitrary number satisfying m>

1.

6. The radio frequency receiver as set forth in claim 5, further comprising:

a band-pass filter for receiving radio frequency signal, and for causing radio frequency signal within a band including the frequency of the radio frequency carrier wave to pass through the band-pass filter; and

a low noise amplifier for amplifying the radio frequency signal having passed through the band-pass filter.

7. The radio frequency receiver as set forth in claim 5, further comprising:

a low-pass filter for carrying out a low-pass filtering with respect to the base-band signals generated by the frequency conversion circuit, the base-band signals having different phases; and

an amplifier for amplifying the base-band signals.

8. A radio frequency transceiver, comprising:

a radio frequency receiver for receiving a radio frequency carrier wave having a desired frequency; and

a radio frequency transmitter for transmitting a carrier wave having a radio frequency,

said radio frequency receiver, including;

a frequency conversion circuit for downconverting a radio frequency signal having a desired frequency into two base-band signals having different phases,

said frequency conversion circuit, including;

a first mixer for mixing the radio frequency signal with a first oscillation signal so that the radio frequency signal is downconverted into an intermediate frequency signal; and

a second mixer for mixing the intermediate frequency signal received from the first mixer with two second local oscillation signals having different phases, respectively, so that the intermediate frequency signal is downconverted into the two base-band signals,

the two second local oscillation signals having phases of 0° and

270°

, respectively, and

f_LO1=k×

f_RF, f_LO2=f_LO1/m, and k=m/(m−

1) being satisfied, where f_RF indicates a frequency of the radio frequency signal, f_LO1 indicates a frequency of the first local oscillation signal, f_LO2 indicates a frequency of the second local oscillation signal, k indicates an arbitrary number satisfying k>

1, and m indicates an arbitrary number satisfying m>

1.

9. The radio frequency transceiver as set forth in claim 8, wherein:

the radio frequency transmitter includes a quadrature modulator for upconverting the base-band signals directly into a radio frequency signal having the frequency f_RF,

the quadrature modulator, including;

a third mixer for mixing an in-phase component of the base-band signal with a clock signal having the frequency f_RF and a phase of 0°

; and

a fourth mixer for mixing a quadrature component of the base-band signal with a clock signal having the frequency f_RF and a phase of 90°

.

10. The radio frequency transceiver as set forth in claim 9, further comprising:

an oscillator for generating the first local oscillation signal;

a divider for dividing the frequency of the first local oscillation signal into 1/m so as to generate the second local oscillation signals having phases 0° and

270°

, respectively;

a fifth mixer for mixing the first local oscillation signal generated by the oscillator with the second local oscillation signal, having the phase of 0°

, generated by the divider so as to generate the clock signal having the frequency f_RF and a phase of 0°

; and

a sixth mixer for mixing the first local oscillation signal generated by the oscillator with the second local oscillation signal, having the phase of 270°

, generated by the divider so as to generate the clock signal having the frequency f_RF and a phase of 90°

.

11. The radio frequency transceiver as set forth in claim 9, wherein:

the radio frequency transmitter further includes;

a low-pass filter for limiting bandwidth of in-phase component and quadrature component of base-band signals obtained by carrying out analog conversion with respect to a digital data that is to be transmitted; and

an amplifier for amplifying electric power of the radio frequency signal upconverted by the quadrature modulator.

12. The radio frequency transceiver as set forth in claim 9, further comprising:

a signal generator for generating the first local oscillation signal and the second local oscillation signals, and for sending the first and second local oscillation signals to the frequency conversion circuit provided in the radio frequency receiver,

wherein;

the signal generator generates clock signals used for the upconversion in the radio frequency transmitter, and sends the clock signals to the radio frequency transmitter.

13. The radio frequency transceiver as set forth in claim 12, further comprising:

an antenna for receiving the radio frequency carrier wave, the antenna being so designed as to operate efficiently at the desired frequency; and

switching means for switching between (i) a receiving mode in which the switching means connects the antenna to the radio frequency receiver and (ii) a transmitting mode in which the switching means connects the antenna to the radio frequency transmitter,

circuit components, for generating the clock signals, in the signal generator stopping operating during the receiving mode.